They are just children, or minors, and they aren't matured enough. If they make mistakes like stealing, then maybe we should also reflect a bit if we do our job as parents to guide them, because children will not steal if they know in the first place that stealing is bad and they'll be punish. It's very challenging nowadays since children can get information online, can talk to people they don't know online, and sometimes we can't see everything they are doing.
Come to Asian countries and our parents will teach you how to handle your kids. Sometimes these gentle things destroy kids' lives. Asian parents used to beat their children for such mistakes. I don't think it's too bad to guide your kids in a hard way. Especially when it comes to stealing and gambling (two offenses at the same time).
Look, if your kid has stolen money to buy chocolate or a toy, then it's okay to guide him gently by saying it's a bad thing to do. But when your children steal money to gamble, that means he has grown enough to understand gambling and they deserve to be punished in hard way.